Limiting number of characters to three positions (ranging from 0–100)

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Lisa M 2020-2-9

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https://ww2.mathworks.cn/matlabcentral/answers/504445-limiting-number-of-characters-to-three-positions-ranging-from-0-100

回答： Lisa M 2020-2-9

So far the code restricts character responses to keys 0-9. However you could type 300. I would like to limit the response in a way that only 0–100 responses are possible. Any suggestions? Thanks in advance.

string = '';
while true
    
    % assemble the cue/target display
    output = [msg, ' ', string];
    % show it
    Screen('CopyWindow',origwindow, windowPtr);
    Screen('DrawText', windowPtr, output, x, y, textColor, bgColor);
    Screen('Flip', windowPtr,0);
    char = GetChar;
    switch (abs(char))
        case {13, 3, 10}
            % ctrl-C, enter, or return
            return;
        case 8
            % backspace
            if ~isempty(string)
                string = string(1:length(string)-1);
            end
            %  0-9
        case {48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58}
            string = [string, char];
    end
end